Background and Aim: The stress of cancer diagnosing prepare situation for many psychological disorders. The objective of this study is to evaluate the effectiveness of acceptance and commitment therapy on reducing depression in Cancer Patients.

Method: This research was a semi-experimental study including pre-test, post-test and control group in which the statistical society consisted of patients with cancer who referred to cancer radiotherapy center of khorram abad in summer of 2016. The samples included 30 patients with cancer who were selected based on DSM-IV distinctive standard and Beck depression inventory and then assigned randomly in two groups of experimental (15) and control (15). The experimental group was treated by acceptance and commitment therapy in 12 sessions, and the control group received no psychotherapy. The data were analyzed by covariance analysis using version 21 of SPSS software.

Results: The results of study showed this kind of psychotherapy can significantly reduce depression in experimental group (P < 0/001).

Conclusion: acceptance and commitment therapy reduce depression in Cancer Patients. This kind of psychotherapy because of increasing psychological resilience, connecting patient to present and also leading to committed acting to personal values, can be one of the best psychotherapies for reducing depression in cancer patients.